The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Turbine generators typically include bypass valves, often part of a main valve, that permit only a portion of the normal flow through a conduit to pass to another portion of a conduit. Such bypass valves may be useful when starting up a turbine generator so as to more gradually warm the turbine generator to its operating temperature.
It is not uncommon for the fluid flowing through the main valve and/or the bypass valve to erode the various components in the valves over a period of time. Erosion of the valves and its components may lead to reduced performance and increased maintenance costs to repair and replace the eroded or worn parts.
The bypass valve may be at greater risk of erosion than the main valve. The bypass valve, by its very nature, may be opened only a small amount to limit the amount of flow through the bypass valve. Of course, with a restricted flow area, the velocity of a fluid at a given pressure will be relatively higher than it otherwise would be were the bypass valve opened a greater amount. Thus, the relatively higher velocity of any fluid through the bypass valve may cause greater erosion than might occur were the velocity of the fluid slower. Further, any entrained solids or other constituents in the fluid further increases the risk of erosion occurring.
The geometry of the bypass valve, too, plays a role in the risk of erosion occurring. Typically, the flow of fluid is redirected as it passes around and through the bypass valve, risking greater erosion than would otherwise occur in the absence of any change in direction. Previous designs of bypass valves have included valve tips with rounded or swirled geometries that it was hoped would reduce erosion. Such designs, however, have been unsatisfactory in reducing erosion within the bypass valves.